Molly Williams, nine, was born with a rare form of motor neurone disease, meaning she will never walk or stand without support.
But siblings Anya and Edmund are spending time training with firefighters at Parkway Fire Station as she gears up to complete 84 laps of an athletics track - a lap for every night she’s spent in critical care.
Group Manager Paul Bragger, said: “When we heard about Molly’s incredible fundraising challenge, our firefighters were only too happy to meet Molly and help her prepare.
“Crews have been so inspired they are planning a string of their own events in support of her fundraising efforts, including 100 climbs of our 32 metre turntable ladder- which is no mean feat!”
Full-time wheelchair user Molly has already undergone two, ten hour surgeries at Sheffield Children’s Hospital - straightening her spine with rods and reconstructing both her hips.
Sometimes she needs a special mask to breathe.
The Royal Air Forces Association has supported her by providing specialist equipment to improve her quality of life - prompting Molly and her family to launch their fundraising challenge.
Her former RAF mechanic dad Julian is running and walking 100 miles in one mammoth 24 hour session.
Meanwhile Molly, mum May, sister Anya and brother Edmund will complete 84 laps of a 220 metre indoor athletics track on her duet tandem wheelchair bicycle.
The challenge takes place on 28 and 29 May at the English Institute of Sport and Olympic Legacy Park, Sheffield.
For more information or to donate, visit http://www.justgiving.com/fundraising/100miles4molly